Stable and ligand-free gold nanoparticles produced by laser ablation as efficient electrocatalysts for electrochemical sensing of dopamine

The possibility of producing high-purity and ligand-free nanoparticles makes laser ablation in liquids (LAL) an interesting method to produce gold nanoparticles (AuNPs). AuNPs play an important role in the manufacture of electrochemical sensors due to their excellent electrical conductivity and chemical stability. In this study, stable and ligand-free AuNPs were produced by LAL (AuNP/LAL) using a nanosecond pulsed laser. The control of this single-step production was facilitated by adding sodium chloride (NaCl), resulting in the reduction of AuNPs size (10 ± 2 nm) and higher stability (monitored for 12 weeks). The potential of NaCl-stabilized AuNPs/LAL as modifiers agents were investigated for dopamine (DA) sensing by cyclic voltammetry for the first time. The novel electrochemical sensor (GCE/AuNPs.LAL/Nafion) achieved an increase in the peak current of ca. 3 and 6 times for oxidation and reduction, respectively. A comparison of chemical syntheses and LAL approaches was given for electrochemical sensing applications; the AuNPs/LAL showed to be more efficient in facilitating the electronic transfer and electrocatalytic reactions. The estimated limit of detection values for DA sensing was 0.77 µmol/L (oxidation) and 1.08 µmol/L (reduction). The method hereby proposed is promising for clinical applications as the new electrochemical sensor allowed proper sensitivity for DA.